The invention relates to a bottom valve, defined in the preamble of claim 1, for a motor-vehicle double-tube shock absorber.
As regards such a bottom valve, the quantity of oil displaced by the piston dipping into the oil generates the pressure-damping force. In general this feature is implemented using variably prestressed valves, disks or packs of disks in cooperation with boreholes and/or similar aperture""s cross-sections.
The objective of the invention is to create a bottom valve also suitable for higher damping forces and exhibiting the feature that the damping characteristic line can be adjusted between the shock absorber""s compression speed of 0 m/s and the opening point OP of the main damping valve.
This goal is attained by a bottom valve includes a main damping valve for the main-force control borehole and a bypass control-borehole which determines the damping behavior before the main damping valve is opened. A prestressed bypass valve acting as a pressure relief valve cooperates with this bypass borehole. By appropriately positioning this bypass valve and/or selecting the prestressing spring for it, it is possible to attain a desired damping characteristic line until the main damping valve is opened. Advantageously the bypass valve shall be set at a fixed prestressing force at its adjustment height relative to the control borehole using an adjustment bolt accessible outside the shock absorber.